JPS6013920A - Intake apparatus for multi-cylinder engine - Google Patents

Abstract

PURPOSE:To obtain a high volumetric efficiency over a wide range of engine operation, by communicating two divided passages with each other via a connecting passage having a first valve means, and providing a second valve means between the portions of a volumetric section where the two divided passages are opened. CONSTITUTION:Divided passages 7 and 8 are communicated with each other via a connecting passage 12 having a poppet valve 13, and a butterfly valve 11 is provided between the portions of a volumetric section 3 where the two divided passages 7, 8 are opened. By closing the butterfly valve 11, a high volumetric efficiency of an engine is obtained at the time of its low-speed operation. By opening the poppet valve 13 subsequently, a high volumetric efficiency is obtained at the time of medium-speed operation of the engine. Further, by opening the butterfly valve 11, a high volumetric efficiency is obtained at the time of high-speed operation of the engine.

Description

Detailed Description of the Invention Technical Field The present invention relates to an intake system for a multi-cylinder engine, and more particularly to a technique for improving the volumetric efficiency of an engine by appropriately selecting the effective length of an intake pipe and utilizing inertial supercharging. .

Japanese Utility Model Publication No. 57-156067 discloses a configuration in which two separate intake pipes are connected to an air vessel and a valve device is built in the air vessel. This valve device is opened and closed depending on the engine load, and is designed to provide a large inertial supercharging effect both at low speeds and at high speeds. However, in recent internal combustion engines, in addition to improving the output at high speeds and high loads, there has been a strong push to improve the direction of output and fuel efficiency during light to medium load operation suitable for city driving, for example. The requirements for a wide operating range are often not fully met by the prior art configurations described above.

OBJECTS OF THE INVENTION The object of the present invention is to improve the above-mentioned type of intake system and to obtain an intake system that provides a high volumetric efficiency over a wide range of operating ranges.

Structure of the Invention The present invention provides two air cleaners separated on the downstream side of the air cleaner.
The intake passages of 2f[lj are connected to a single volume part, and the intake passages from this volume part to each cylinder are branched, and the separation passages of 2f[lj are communicated with each other by a communication passage, and the first valve device is connected thereto. a second valve device is arranged in the volume between the openings of the two separation passages, and a second valve device is arranged in the volume between the openings of the two separation passages;
The present invention provides an intake system for a multi-cylinder engine, which is characterized in that the valve system is operated independently according to the engine load.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an intake system for a multi-cylinder engine according to the present invention. A diesel engine 1 is equipped with an intake pipe 2 that communicates with each cylinder. Each cylinder pipe 2 is connected to a single volume 3 to form an intake manifold. An exhaust manifold 4 is attached to the engine 1 in a well-known manner.

The intake pipe 6 connected from the air cleaner 5 is separated into two intake pipes 7, 8, which open into the volume 3 at 9, 10. The volume part 3 has openings 9,1
A control valve 11 made of a butterfly valve is arranged between the two.

The separated intake pipes 7 and 8 are communicated with each other by a communication pipe 12 at an appropriate position along the air flow direction, and a control valve 13 made of a poppet valve is arranged in the communication part. Although driving devices for these control valves 11 and 13 are omitted, they can be driven by techniques well known in the art.

The butterfly valve 11 is opened at high speeds to provide a common large volume to each cylinder, and as shown by the dashed line A in FIG. 2, the volumetric efficiency is improved in the high engine speed range. In this case, opening and closing of the poppet valve 13 is substantially irrelevant since the volume is located closer to each cylinder.

When the butterfly valve 11 is closed, the common volume virtually disappears and becomes a small volume separated by the butterfly valve 11, which is connected to the separate intake pipes 7, 8, respectively.
become part of. The advantages of separate intake pipes are described in the above-mentioned publications.

Opening and closing the poppet valve 13 with the butterfly valve 11 closed means that the effective length of the separate intake pipes 7, 8 changes substantially, which leads to a change in the volumetric efficiency with respect to the engine speed. Become. For example, when the poppet valve 13 is closed, a volumetric efficiency curve shown by the dashed double-dashed line B in FIG. 2 is obtained, and when the poppet valve 13 is open, a volumetric efficiency curve shown by the broken line C is obtained. Therefore, butterfly valve 11 and poppet valve 1
3 is opened or closed at the rotational speed corresponding to the intersection of curves A, B, and C in Fig. 2, a volumetric efficiency curve as shown by the solid line X in Fig. 2 is obtained, and from low speed to high speed. High volumetric efficiency can be obtained over a wide range.

Effect: Volumetric efficiency can be increased over a wide range in this way, making it possible to not only obtain high output at high speeds, but also increase engine output at light and medium loads, making it easier to shift gears at least when driving around town. Change frequency decreases. This not only improves drivability but also saves fuel consumption.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an intake system for a multi-cylinder engine according to the present invention;
FIG. 2 is a graph showing volumetric efficiency. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake pipe, 3... Volume part, 5...
・・Air cleaner, 7, 8・・Separate intake pipe, 11・・
・Butterfly valve, 13...Poppet valve. Patent applicant Toyota Motor Corporation Patent application agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Kyosuke Tsuchinakayama Patent attorney Akira Yamaguchi

Claims (1)

[Claims] Two intake passages separated on the downstream side of the air cleaner are connected to a single volume part, the intake passages from the volume part to each cylinder are branched, and the two separated passages are communicated with each other by a communication passage. A first valve device is disposed therein, and a second valve device is disposed in the volume between the openings of the separation passages of the 2fllj.
An intake system for a multi-cylinder engine, characterized in that the first valve device and the second valve device are independently operated according to the engine load.